LE American & cross-head pumps?

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DianneB
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LE American & cross-head pumps?

Post by DianneB » Tue Oct 10, 2017 5:03 pm

Is anyone running a Little Engines American, particularly an early design, and using cross-head pumps?

The pumps on my LE American don't quite keep up with the water requirements. I want to fix that this winter!

I don't know if I am loosing too much steam or if my pumps aren't working efficiently. I plan to take the pumps off this winter, check for wear, and repack them. I will also take the check valves off and give them a good vinegar cleaning and then check they are sealing properly. I don't, however, know if the pumps have enough displacement to keep up with the steam requirement so I'd like to know other people's experience.

Thanks gang!

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Dick_Morris
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Re: LE American & cross-head pumps?

Post by Dick_Morris » Tue Oct 10, 2017 5:19 pm

It's a bigger locomotive, but my RRSC CP-173 started with one crosshead pump (5/16" bore?) and I had to add a second to keep up with demand. I found that the effort to pump the water when the boiler was close to full pressure caused the pull from the locomotive to be noticeably jerky. The crosshead pumps are still there but now the water is typically put in with an injector.

James Powell
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Re: LE American & cross-head pumps?

Post by James Powell » Tue Oct 10, 2017 9:49 pm

Dianne, if you figure out the water:steam ratio between the volume of the feed pump and the volume of the cylinders, that will tell you. I would expect that on a 7.x gauge engine, a ratio of about 1.5x the steam volume is required to get ahead or stay ahead. If you have the space, what Dick is saying is good advice- putting a 2nd pump on the opposite crank is probably better than making one large pump. In principal, I think you would find that two large bore, short stroke pumps setup to pump at the middle of the rearward stroke of the steam piston is "best", but that may be hard to arrange unless the pumps are inside the frames driven by excentrics. I can't remember what Harry Allen's American had, it might have been injector rather than feed pump.

James

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Dick_Morris
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Re: LE American & cross-head pumps?

Post by Dick_Morris » Wed Oct 11, 2017 12:58 am

I forgot to mention the jerkiness is exacerbated by the two crosshead pumps pressure strokes being 90 degrees apart. With a two cylinder pump driven by eccentrics from an axle the strokes can be 180 degrees apart.

Are you operating at the top pressure allowed for your boiler? Less makeup water is required at a higher operating pressure. Could you fit a "steam dryer" so that your steam to the cylinders is less wet?

Many little locomotives have cylinders that are bigger than needed. If you can easily slip the drivers, you need to do surgery, maybe sleeving and reboring the cylinders would be more practical than increasing delivery from the pump.

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DianneB
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Re: LE American & cross-head pumps?

Post by DianneB » Wed Oct 11, 2017 6:21 am

The American has two cross-head pumps, 1/4" diameter, 2" stroke. Cylinders are 1.376" diameter.That gives a pump volume of 0.098 cu. in and cylinder volume of 2.972 cu. in. giving a ration of 30.29.

I operate with a 100 PSI safety and usually run between 80 and 100 PSI. If it is the original boiler, it is 55 years old and (I believe) the LE boiler was designed for 100 PSI operation.

I am NOT interested in modifying the cylinders. Yes, the American can be 'slippery' but that's part of the challenge of driving.

What I was looking for was anyone else's experience in running a Little Engines American to see if mine is behaving "normally" for its type.

I have an injector I can add and I am planning to add a duplex steam pump. (I have the Van Brocklin plans and Bill Shield's version as well but EVERYBODY in my club has Van Brocklin pumps and I'd rather do something different so I am working up plans for a Worthington duplex pump.)

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Fred_V
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Re: LE American & cross-head pumps?

Post by Fred_V » Wed Oct 11, 2017 7:39 am

I have a crosshead pump on my Chloe and it will over fill the boiler. I hardly notice any jerking.
Fred V
Pensacola, Fl.

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cbrew
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Re: LE American & cross-head pumps?

Post by cbrew » Wed Oct 11, 2017 8:28 am

here is an idea to consider. replace the old pumps with a pair of all the shelf double acting stainless air cylinders from a vendor like Clippard.
the advantages are
1) moving water forward with each direction.
2) with two, they will always be moving water, either to the boiler or back to the tender. no jerking.
3) easy replacement if one goes back

disadvantages
1) due to the tight space, may not be due able
2) double the current hardware (checks, piping, etc.

just a thought
or just hold out for one or pair of Anthonys small injectors

https://www.eccentricengineer.com/injec ... s-injector
If it is not live steam. its not worth it.

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DianneB
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Re: LE American & cross-head pumps?

Post by DianneB » Wed Oct 11, 2017 8:58 am

cbrew wrote:here is an idea to consider. replace the old pumps with a pair of all the shelf double acting stainless air cylinders from a vendor like Clippard.
No space
or just hold out for one or pair of Anthonys small injectors
I HAVE an injector.

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cbrew
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Re: LE American & cross-head pumps?

Post by cbrew » Wed Oct 11, 2017 9:27 am

ok, I have worked on my buds LE american a good bit and i seem to remember enough room between the crosshead and frame, it was just a idea, carry on
If it is not live steam. its not worth it.

rrnut-2
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Re: LE American & cross-head pumps?

Post by rrnut-2 » Wed Oct 11, 2017 11:14 am

The cross head pumps on my LE American did not keep up with the water usage and we used the injector and the hand pump to make up the
difference. If the rams are increased in size, then the "jerkiness" of the locomotive becomes more pronounced. In the end, I left everything
alone and my wife and I ran it with the original pumps.

Jim B

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DianneB
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Re: LE American & cross-head pumps?

Post by DianneB » Wed Oct 11, 2017 11:54 am

rrnut-2 wrote:The cross head pumps on my LE American did not keep up with the water usage.....
Thank you Jim that is EXACTLY the info I was looking for!

jessebanning
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Re: LE American & cross-head pumps?

Post by jessebanning » Thu Oct 12, 2017 10:50 am

The original crosshead pumps on the American were .1875" diameter rams, later they became .250" which added a little more displacement. I am currently building two of these engines and will find out if the larger bore was sufficient.
www.banninglocomotiveworks.com

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